Establishing Changes in the Technical Parameters Of

Eastern-European Journal of Enterprise Technologies ISSN 1729-3774 2/1 ( 104 ) 2020

UDC 637.115 Дійкова гума – важлива частина доїль ного апарату, один з його ключових еле DOI: 10.15587/1729-4061.2020.200635 ментів. Це той єдиний компонент доїль ної установки, який має безпосередній контакт з поверхнею вимені корів. Поряд ESTABLISHING CHANGES IN з цим, дійкова гума – це самий наван THE TECHNICAL PARAMETERS тажений компонент доїльного апарату. За час процесу доїння вона стискається OF NIPPLE RUBBER FOR і розтискається понад 400 разів. З метою максимального ефекту від використання MILKING MACHINES AND THEIR дійкової гуми, необхідно правильно розра хувати умови її використання, своєчас IMPACT ON OPERATIONAL но здійснювати контроль технічних па- раметрів. Завдання дослідження полягає CHARACTERISTICS у встановленні змін технічних парамет рів дійкової гуми доїльних апаратів та їх A. Paliy впливу на експлуатаційні характеристи Doctor of Agricultural Sciences, Associate Professor* ки виробу. E-mail: [email protected] В ході досліджень встановлено, що А. Nanka працездатність всіх дійкових гум скла PhD, Professor, Rector** ла 1000 годин, що при напрацюванні в M. Marchenko день восьми годин відповідає 125 дням або PhD, Associate Professor* 4 місяцям експлуатації. При напрацюван V. Bredykhin ні в 1000 годин жорсткість дійкової гуми PhD, Associate Professor коливається в значних межах і в серед Department of Physics and Theoretical Mechanics** ньому становить: для виробів з силікону A. Paliy 2849,61 ± 52,23–3343,76 ± 51,26 Н/м; з мате Doctor of Veterinary Sciences, Professor ріалу гумових сумішей – 2597,76 ± 78,26– Laboratory of Veterinary Sanitation and Parasitology –2821,43 ± 55,24 Н/м. Коефіцієнт готовнос National Scientific Center «Institute of Experimental ті усіх виробів становить 1. За викори and Clinical Veterinary Medicine» стання електронної мікроскопії встанов Pushkinska str., 83, Kharkiv, Ukraine, 61023 лено зміни внутрішньої поверхні дійкової J. Negreba гуми після напрацювання 125 днів/1000 го- Senior Lecturer*** дин та після експлуатації протягом L. Lazorenko 250 днів/2000 годин. Доведено, що змінам Senior Lecturer*** під час експлуатації дійкової гуми під даються всі основні її параметри. Маса A. Panasenko виробу змінюється на 8,5 %, глибина – на PhD, Senior Lecturer 37 %, товщина стінок – 2,5 %, а довжина Department of Virology, Pathology of Poultry Diseases**** розтягнення – на 27 %. Між жорсткістю Z. Rybachuk дійкової гуми та інтенсивністю молоковід PhD, Associate Professor дачі встановлено високу позитивну коре Department of Microbiology, Pharmacology and Epizootology ляційну залежність (r=+0,939). Polissia National University Досліджені показники є важливими у Staryi blvd., 7, Zhytomyr, Ukraine, 10008 визначенні працездатності та придатнос O. Musiienko ті дійкової гуми до використання. Проведе- PhD, Associate Professor ні дослідження представляють реальну Department of Therapy, Pharmacology, можливість врахування якісних парамет Clinical Diagnostics and Chemistry**** рів дійкової гуми доїльних апаратів під час *Department of Technical Systems and Animal Husbandry Technologies** вибору та подальшої експлуатації **Kharkiv Petro Vasylenko National Technical University of Agriculture Ключові слова: дійкова гума, доїльний Alchevskih str., 44, Kharkiv, Ukraine, 61002 апарат, доїльний стакан, контроль пара ***Department of Epizootology and Parasitology**** метрів гуми, експлуатація дійкової гуми ****Sumy National Agrarian University Herasym Kondratiev str., 160, Sumy, Ukraine, 40021

Received date 14.01.2020 Copyright © 2020, A. Paliy, А. Nanka, M. Marchenko, V. Bredykhin, Accepted date 09.04.2020 A. Paliy, J. Negreba, L. Lazorenko, A. Panasenko, Z. Rybachuk, O. Musiienko Published date 27.04.2020 This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0)

1. Introduction depends on many factors associated with the physiological state of an animal. The share of this process accounts for Machine milking is one of the most complex production about 50 % of the total labor costs of a dairy herd servicing. processes at a dairy complex. The effectiveness of its use Unlike manual milking, machine milking facilitates and sim-

78 Engineering technological systems: Reference for Chief Mechanical Engineer at an industrial enterprise

plifies the work of operators and increases performance by occurring in the compression cycle. As soon as the atmo- several times [1, 2]. spheric air begins to fill the interwall space of a milking cup, Modern milking equipment during operation should pro- the rubber loses its shape and becomes flattened in the shape mote the realization of a full-fledged milking process of cows, of an eight or an ellipse in the transverse direction. exclude the possibility of blood circulatory disorders, ensure To determine the degree of significance of the factors natural parameters of the magnitude of vacuum and take into affecting the nature of the movement of the wall of nipple consideration individual characteristics of an animal [3]. rubber, the mathematical model of the process of nipple The quality of milking cups is of particular importance [4]. rubber compression was developed and explored [12]. It was Its wear occurs due to the negative impact of water, milk fat, established that the degree of influence of the structural and detergents, sunlight, changes in temperature. Because of these physical-mechanical parameters within the limits that meet factors, nipple rubber loses its elasticity, there occur micro the physiological needs of animals is insignificant. cracks that badly injure the udder nipples during milking. The studies [13] revealed that during using worn-out A cow during the milking process feels pain, which inhibits nipple rubber, 5 % of milk yield is lost. This leads to incom- milk giving and, consequently, the time of milking increases. plete milking of a cow, resulting in a loss of up to 12 % of milk The technical characteristics of nipple rubber are the factors fat and significant damage to the animal’s overall health. that determine the character of rubber operation during milk- According to research [14], the magnitude of pressure on ing, and, consequently, its effect on the animal organism. There- the end of the udder nipple depends mainly on the following fore, the rubber article of a milking cup should be given due factors: the thickness and stiffness of nipple rubber, the mag- attention. Thus, the need to study the operational characteris- nitude of its tension in a milking cup, and working vacuum. tics of nipple rubber implies the need to establish the changes in Previously conducted research into the operational its technical parameters that occur during its being used under properties of nipple rubber was carried out with the pre- production conditions. This is achieved by the establishment of known time of their operation, which excluded the possibili- work efficiency of nipple rubber of various manufacturers after ty of establishing the changes in parameters during its phased 125 days/1,000 hours of operation with subsequent studying operation period. In addition, based on these studies, it was the inner surface of nipple rubber using electron microscopy. difficult to make a comprehensive assessment of the duration This approach will make it possible to expand the idea of using nipple rubber [15]. of the mechanism of changes in nipple rubber occurring in The material from which nipple rubber is made is pre- the process of its operation and will lead to the rational use dominantly a rubber mixture. At the same time, the use of of rubber articles of milking machines, therefore, will bring silicone articles with many advantages is considered to be the practical benefits. Thus, the research of this kind is relevant. most effective nowadays [16]. Silicone rubber first appeared in the market in 1944 and since then it has been increasingly used in everyday life, particularly in the food industry. 2. Literature review and problem statement Papers [17, 18] focus on the issue of milking equipment functioning. They emphasize the functioning of the separate The analysis [5, 6] in the field of dairy farming has shown elements of milking plants, their impact on the technological that a decrease in the losses of cows’ milk productivity and an process of milking. Thus, the pulse characteristics of nipple increase in the quality of obtained milk depend on numerous rubber and calculated data of pulsors’ operation were outlined factors. These include the motor function of the breast, ad- theoretically and the performance of a manipulator was pre- vanced and normed feeding, reproduction of animals for many sented as a narration. However, the issues, related to the re- years of operation under the conditions of industrial complex- search into performance characteristics of nipple rubber made es, prevention and early diagnosis of mastitis, improvement of from different materials directly in production conditions, the technology of machine milking, etc. However, the biggest remain unresolved. The reason for this is objective difficulties milk losses (≈50 %) are caused by technical reasons because associated with the access to dairy complexes, fundamental the design and operating modes of milking machines fail to inability to manipulate the milking herd, the expenditure part meet the physiological needs of animals [7]. as for the terms of the relevant research and observations. The main tasks in the development of mechanisms of milk- It can be argued that it is advisable to research the estab- ing are the elimination of structural shortcomings and causes, lishment of changes in the technical parameters of the nipple leading to the inhibition of milk yield, achievement of a reliable rubber of milking machines that are observed during operation. interaction of an executive mechanism and an animal, ensuring the simplicity and operational reliability of a structure [8]. Thus, paper [9] emphasizes the need for a more detailed review of the 3. The aim and objectives of the study features of nipple rubber operation – the most important executive mechanism of a milking plant, which directly interacts with The aim of this study is to establish the changes in the the animal’s body. It is this element that is in direct contact with technical parameters of nipple rubber for milking machines and a cow’s udder nipple. During milking, nipple rubber is designed their impact on the operational characteristics of this product. to protect the nipple from the effect of a high vacuum and To achieve the set aim, the following tasks should be solved: restore the normal blood circulation in it. In fact, during com- – to establish experimentally the workability of nip- pression tact, the rubber has a traumatic action, flattening in the ple rubber of various manufacturers after operating for form of a slit and deforming an udder nipple in one plane. In this 125 days/1,000 hours and to prove their suitability for use; case, the nipple tip acquires a bilateral flattened appearance, the – to explore the inner surface of nipple rubber using elec- sphincter is pressed and opens passively, exposing the nipple and tron microscopy; the inner cavity of the udder to the action of deep vacuum [10]. – to determine the patterns of changes in the technical The study [11] in the field of flexible shells, which in- parameters of nipple rubber and to establish the nature of clude nipple rubber, reveals the mechanism of phenomena their influence.

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4. Materials and methods to study the tail part of the nipple rubber were measured according to the technical parameters of nipple rubber for scheme in Fig. 2. milking machines

4. 1. Procedure for studying the workability of nipple rubber by various manufacturers The experiment was carried out at the State enterprise «Experimental farm «Gontarivka» in the Vovchansk district of Kharkiv oblast (Ukraine) at the tied keeping of dairy cows а of the Ukrainian black-spotted milking breed. The animals are milked into the milk pipeline. The average milk yield was 6,750 kg during preliminary lactation. The average fat content of milk was 3.8 %. The water used to wash the system was at t 40–45 C = ° b and had a general stiffness of 6.4 mol/m3. According to the procedure [19], we maintained the conditions of sampling and conducted an initial examination of articles, established the suitability for tests, found faulty rubber. We followed the algorithm for testing nipple rubber, used the approaches and manipulations that are necessary during the test works. In particular, we measured the elastic proper- c ties of rubber in order to determine its stiffness by absolute extension at the applied load of 58.86 N for 10 s. Stiffness of nipple rubber under the load of 58.86 N was determined according to [20]. As the magnitude that is directly proportional to the d module, stiffness is a material characteristic of a rubber arti- Fig. 1. Nipple rubber represented in the study: cle and has its calculated value. Eq. (1) makes it possible to а – nipple rubber of brand DD.00.041А from silicone (food find stiffness C experimentally. silicone); b – nipple rubber of brand DD.00.041А from P silicone FСІ-55P (food silicone); c – nipple rubber of brand C = , (1) DD.00.041А from the material of rubber mixtures (black Δl rubber); d – nipple rubber of brand DD.00.041А from the material of rubber mixtures (black rubber) where С is the stiffness of nipple rubber, Р is the pressure by the load of 58.86 N, Δl is the total stretching, mm. The study presented: To conduct research, 2 milking machines were equipped – 10 pieces of rubber DD.00.041А from silicone pro- with nipple rubber No. 1 from food silicone, as well as 2 milk- duced by VAT «EuroAgroTech», the city of Krasnodar (Rus- ing machines were equipped with nipple rubber No. 2 from sia) – No. 1; silicone FCI-55P, 2 milking machines – with nipple rubber – 10 pieces of rubber DD.00.041А from silicone FSI-55P No. 3 and 2 milking machines – with rubber article No. 4. produced by AT «Stoimash», the city of Cheboksary (Chu- The remaining rubber was left as spare parts. vash Republic) – No. 2; Reliability indicators of rubber elements were deter- – 10 pieces of rubber DD.00.041А from the material mined by lengthy multiple tests of their small quantity and of rubber mixtures produced by АО «Bratslav» the settle- statistical processing of test results. The readiness coeffi- ment of Bratslav, Nemirov district of Vinnytsia oblast (Uk- cient (Kg) of the samples of nipple rubber was determined raine) – No. 3; from formula (2). – 10 pieces of rubber DD 00.041А from the material of rubber mixtures produced by ВАТ «Rezinotechnika», the Ns()t Kg = , (2) town of Borysove (Belorus) – No. 4. Nt ()t The represented samples were made based on silicone and rubber mixtures (Fig. 1). where Ns(t) is the number of serviceable rubber elements at Rubber is a single part with a milk nozzle and has three moment of time, Nt(t) is the total number of elements. locking ring grooves, which makes it possible to pull it in a The research materials were processed and analyzed with milking cup as it is stretched during the operation. the help of the standard package of licensed applied statisti- At the initial stage, using the geometric measurements, cal application SPSS – 12.0. it was established that all the presented articles fully comply The correlating dependence was found by a correlation with all the technical specifications [21] (Table 1). coefficient of Pierson r, which is a dimensionless index in the The lack of data on technical conditions [21] (in Table 1 range from – 1.0 to 1.0 inclusively and reflected the measure (–)) is explained by a wide variability of the above indica- of linear dependence between two datasets. tors, which is proved in article [18]. The research results were processed by the method The parameters of nipple rubber, which were subjected to of variation statistics based on calculating the arithmetic measurement during the research, are shown in Fig. 2. mean, deviation of indices from the arithmetic mean error Thus, the length of the operating part of the article, the and reliability of the difference between the comparable diameter of the suction cup and the inner diameter of the indicators.

80 Engineering technological systems: Reference for Chief Mechanical Engineer at an industrial enterprise

Table 1 Technical characteristic of the nipple rubber presented in the research Value of indicator Indicator Technical Data from studying the rubber conditions No. 1*1 No. 2*2 No. 3*3 No. 4*4 Vacuum metric pressure, kPа 48 ± 1 48 48 48 48 Pulsation frequency, pulse/min 65 ± 3 61.2 62.4 62.8 63.1 Ratio of cycles, %: sucking; 60 ± 3 61.2 62.8 62.4 62.7 compression 40 ± 3 39.4 38.1 38.2 38.7 Weight of one article, g 107 97 100 102 103 Length of a milking cup, mm – 159 159 159 159 Length of a milking cup in assembly with rubber, mm – 307 307 308 308 Length of milking rubber, mm – 288 288 292 294 Outer diameter of a milking cup, mm – 41 41 41 41 Inner diameter of a milking cup, mm – 37 37 37 37 Geometrical dimensions, mm: length of operating part; 152 149.8–150.1 149.7–150.3 153.1–155.0 153.1–154.8 diameter of sucking device opening 25.0 25.0–25.3 24.8–25.1 25.3–25.6 25.4–25.6 Outer diameter of tail part 9.0 8.8–9.1 8.8–8.9 8.9–9.1 9.0–9.1 Outer diameter of sucking device 60.0 60.0 60.0 60.0 60.0 Inner diameter of sucking device 27.6 27.6 27.6 27.6 27.6 thickness of walls 2.2 2.2 2.2 2.2 2.2 Stiffness of nipple rubber, N/m – 3,120.46 ± 55.19 3,435.39 ± 64.21 2,842.36 ± 72.23 2,759.77 ± 75.16 Note: *1 – nipple rubber of brand DD.00.041А from silicone (food silicone); * 2 – nipple rubber of brand DD.00.041А from silicone FСІ-55P (food silicone); * 3 – nipple rubber of brand DD.00.041А from the material of rubber mixtures (black rubber); *4 – nipple rubber of brand DD.00.041А from the material of rubber mixtures (black rubber)

– parameters of ranges of voltages of accelerating type are from 0.5 kV to 30 kV; – parameters of multiplication ranges are from 15 to 300,000; – parameters of a range of measurements of dimensions of Fig. 2. Schematic of control over the geometric parameters linear character are from 0.2 to 5,000 µm. of nipple rubber: А – length of operating part of the article; According to the procedure [22], the studied objects D1 – diameter of the suction device opening; D2 – inner had the appropriate dimensions, limited from the top by diameter of the tail part of nipple rubber the dimensions of the operating chamber gateway and were resistant to irradiation with a beam of electrons with a dose 4. 2. Procedure for studying the inner surface of nipple of about 103 µmKl/сm2. The rubber samples were stable and rubber with the use of electron microscopy did not evaporate at the pressure of 10–4 Pа. The specific re- To study the inner surface of nipple rubber, we used raster sistance of the sample material did not exceed the magnitude electron microscope REM-106 produced by VAT «SELMI», of 104 Ohm/сm. the city of Sumy, Ukraine. It is a stationary automated multi-function measuring system. The principle of obtaining 4. 3. Procedure for studying the patterns of changes in the image of REM-106 is to modulate the brightness of the the technical parameters of nipple rubber and for estab- monitor of a video control device by the signals, proportional lishing the nature of their influence to the number of registered secondary electrons when scan- The technical state of nipple rubber was assessed during its ning a focused electronic probe on the surface of an object. installation in the machine and every two months of operation The ratio of the image size on the monitor to the raster after washing and daily «rest». Stretching of special rubber dimensions on the sample is determined by the microscope under the influence of the standard load was measured with multiplication. the help of the technical and technological solutions [20]. The functions of measuring the linear dimensions of ob- In order to determine the performance properties of nip- jects were performed and the quality composition of the ob- ple rubber, the following measures were taken: ject was determined using the method of X-ray microanalysis. – the rubber was washed in the solution of detergents Basic features of the technical device are the following: with the application of brush; – level of resolution in high-level vacuum mode is 4 nm; – the rubber was disinfected and washed; – level of resolution in low-level vacuum mode is 6 nm; – the rubber was placed on the shelf and kept for 10 days – the value of maximum image size is at the level of to restore its shape and size; 1,280×960 pixels; – the visual examination of the rubber state was per- – parameters of pressure regulation range inside the formed to detect defects (cracks, deformations, and changes chamber is from 1 Pa to 270 Pa; in the shape of openings);

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– the length of the rubber was checked and cut off if Table 2 necessary; Parameters of nipple rubber No. 1 after the operation – rubber was arranged according to stiffness. for 125 days/1,000 hours The weight of nipple rubber was determined using the Geometric Stiffness Ovality No. of analytical electronic scales AS 60/C with the liquid crystal dimensions, mm of nipple of cross-sec- indicator that was entered in the State Register of Ukraine article А D1 D2 rubber, N/m tion, % with No. Y 1821-09. 1 150.4 25.3 9.0 3,119.46 ± 55.16 2 The length of nipple rubber was based using a ruler on 2 150.2 25.2 9.2 2,849.61 ± 52.23 4 a tripod: from the base of the sucker to the bottom edge of the third from the sucker of the ring deepening in the place of 3 150.1 25.1 9.2 2,967.36 ± 65.19 3 transition of a sucking part of rubber to the milk pipe. 4 150.1 25.2 9.1 3,018.39 ± 75.12 5 The average intensity of milk yield (Q) in kg/min was 5 150.2 25.1 9.1 3,019.76 ± 49.27 1 calculated from formula (3). 6 150.3 25.1 9.1 2,988.83 ± 65.22 2 7 150.2 25.2 9.2 2,899.37 ± 55.41 4

()qq12+ 8 150.2 25.2 9.1 3,022.31 ± 85.13 3 Q = ∑ , (3) tt Note: P < 0.05 ∑()12+ Table 3 where q1 is the magnitude of machine milking, kg, q2 is the Parameters of nipple rubber No. 2 after the operation magnitude of machine additional milking, kg, t1 is the dura- for 125 days/1,000 hours tion of machine milking, min, t is the duration of machine 2 Geometric Stiffness Ovality additional milking, min. No. of dimensions, mm of nipple of cross-sec- article А D1 D2 rubber, N/m tion, % 1 150.4 25.0 8.8 3,218.58 ± 49.19 2 5. Results of studying the technical parameters 2 150.4 24.9 8.8 3,343.76 51.26 3 of nipple rubber for milking machines ± 3 150.1 24.9 8.9 3,137.71 ± 35.18 1 5. 1. Studying the workability of nipple rubber for 4 150.2 25.0 9.0 3,229.74 ± 65.22 4 milking machines 5 150.3 25.0 9.0 3,176.21 ± 71.36 5 During the examination of the mechanism of operation of 6 150.2 25.2 8.9 3,239.46 ± 61.16 6 nipple rubber, it should be noted that the milking process will 7 150.2 25.0 8.9 3,319.33 ± 75.24 2 occur in more favorable and stress-free situations for animals 8 150.3 25.0 8.9 3,249.49 ± 59.46 3 if we pay due attention to the factors that influence the milk Note: P < 0.05 yield of cows and their health. And such factors, first of all, Table 4 include the operational characteristics of rubber, on which its Parameters of nipple rubber No. 3 after the operation performance depends. for 125 days/1,000 hours To investigate the performance of nipple rubber of milk- Geometric Stiffness Ovality ing machines after their operation for 125 days/1,000 hours, No. of dimensions, mm of nipple of cross-sec- the articles were subjected to measurement of geometric article А D1 D2 rubber, N/m tion, % parameters and the magnitude of closing vacuum. Research 1 154.5 25.5 9.0 2,769.35 ± 45.39 2 results are shown in Tables 2–5. 2 156.0 25.5 9.0 2,811.28 ± 69.19 3 After the operation for 125 days/1,000 hours, the stu died samples had the following magnitudes: the length of 3 155.0 25.7 9.1 2,777.43 ± 65.31 1 the operating part of article (А) No. 1 was 150.1–150.4 mm; 4 155.0 25.7 9.3 2,789.22 ± 85.14 4 of article No. 2 – 150.1–150.4 mm; of nipple rubber No. 3 – 5 155.4 25.6 9.4 2,821.43 ± 55.24 2 154.5–156.0 mm; of rubber No. 4 – 154.5–155.4 mm. The 6 155.6 25.7 9.2 2,793.53 ± 75.31 3 diameter of sucking opening (D1) had the value: of article 7 155.0 25.6 9.2 2,719.93 ± 66.27 2 No. 1 – 25.1–25.3 mm; of nipple rubber No. 2 – 24.9–25.2 mm; 8 155.2 25.7 9.3 2,819.31 ± 59.33 3 of article No. 3 – 25.5–25.7 mm; of rubber article No. 4 – Note: P < 0.05 25.6–25.8 mm. The inner diameter of the tail part of nipple Table 5 rubber (D2) was: of article No.1 – 9.0–9.2 mm; of nipple Parameters of nipple rubber No. 4 after the operation rubber No. 2 – 8.8–9.0 mm; of article No. 3 – 9.0–9.4 mm; of for 125 days/1,000 hours rubber article No. 4 – 8.9–9.4 mm. In this case, the stiffness Geometric Stiffness Ovality of rubber articles had the following values: of article No. 1 – No. of dimensions, mm of nipple of cross-sec- 3,119.46 ± 55.16–2,849.61 ± 52.23 N/m; of nipple rubber No. 2 – article А D1 D2 rubber, N/m tion, % 3,343.76 ± 51.26–3,137.71 ± 35.18 N/m; of article No. 3 – 1 154.6 25.6 9.2 2,750.43 ± 65.32 2 2,821.43 ± 55.24–2,719.93 ± 66.27 N/m; of rubber article 2 154.8 25.6 9.1 2,699.31 ± 74.43 2 No. 4 – 2,751.67 ± 75.16–2,597.76 ± 78.26 N/m. The output parameters of the stiffness of nipple rubber 3 155.0 25.6 8.9 2,685.71 ± 64.25 1 were the data given in Table 1. Thus, after the operation for 4 154.5 25.7 9.3 2,597.76 ± 78.26 4 125 days/1,000 hours, the stiffness of nipple rubber No. 1 5 155.4 25.7 9.4 2,684.73 ± 66.32 5 decreased by 1.1 times. Rubber No. 2 was subjected to the 6 155.2 25.6 9.4 2,671.39 ± 45.24 3 same changes in stiffness (decrease by 1.1 times). Along with 7 155.0 25.6 9.2 2,684.81 ± 55.31 2 this, the stiffness of the samples of rubber articles No. 3 and 4 8 155.2 25.8 9.3 2,751.67 ± 75.16 2 changed within the insignificant limits. Note: P < 0.05

82 Engineering technological systems: Reference for Chief Mechanical Engineer at an industrial enterprise

After the operation for 125 days/1,000 hours of nipple rubber, its ovality of intersection also changed: by 1–4 % (on average 3 by %) of article No. 1; by 1–6 % (on average by 3.3 %) of rubber article No. 2; by 1–4 % (on average by 2.5 %) of article No. 3 and by 1–5 % (on average by 2.6%) of article No. 4. Summarizing the obtained results, it can be argued that after working for 125 days/1,000 hours, all these indicators in the nipple rubber changed. At the same time, its stiffness underwent the biggest changes – by 1.1 times. When milking cows with nipple rubber No. 2–4, the milking machines did not fall off the cow’s udder. When milking cows with nipple rubber No. 1 with the stiffness of 3,119.46 ± 55.16 to 2,849.61 ± 52.23 N/m, there were cases а of milking machines falling off the cow’s udder nipples. The formulations of rubber used by manufacturers have some differences. Thus, a number of companies use rubber with the soot content of not more than 14 %, while in other companies, this value reaches 30 %. This, in turn, causes the differen ces in the operational and technological properties of nipple rubbers, in particular, of the stiffness and character of changes in the technical parameters of rubber during operation. Analyzing the results of research into nipple rubber, it is possible to conclude that these articles are serviceable for 1,000 hours of operation. In this case, their readiness coefficient, determined from formula (2), is 1. b 5. 2. The study of the inner surface of nipple rubber using electron microscopy The state of the inner surface of nipple rubber is of great importance. In order to obtain photographs from the inner surface of nipple rubber DD 00.041A from the material of rubber mixtures produced by AO «Bratslav» (sample No. 3), we used an electronic raster microscope with a low-vacuum chamber and the system of energy disperse microanalysis REM-106. Thus, according to electron microscopy, each point of the sample is sequentially irradiated by the focused electron beam, which moves around the studied surface like scanning of an electron beam in television systems. In the interaction of the probe electrons with the substance, there occur the c corresponding signals of different physical nature (reflec Fig. 4. Inner surface of nipple rubber: а – of a new rubber ted and secondary electrons, Auger-electrons, X-rays, light, article; b – after operation for 125 days/1,000 hours; absorbed current, etc.), which are used for synchronous c – after operation for 250 days/2,000 hours construction of an image on the monitor screen. Thus, the scheme of the study of the inner surface of nipple rubber can be presented as follows (Fig. 3). It was established that the new article has a brilliant glossy inner surface, without any changes (Fig. 3, a). Primary electrons As the term of operation increases, the rubber loses its primary properties, which leads to a decrease in its effective- X-ray irradiation Secondary electrons ness. These processes occur gradually (Fig. 4). Backward scattered electrons Cathode luminescence Rubber wears out due to the dynamic nature of its ope Auger-electrons ration. This element is subjected to the chemical influence of aggressive detergent solutions at elevated temperatures, which leads to the destruction of the inner surface. If we ex- Sample plore the rubber after the operation for 125 days/1,000 hours by the naked eye, it may look clean, but the study under Absorbed electrons Electrons that passed a microscope gives a different picture. Fig. 3, b shows the inner surface of the rubber with magnification – one can be Fig. 3. Scheme of studying the inner surface of the nipple the small areas of growth of the bacterial colonies and surface rubber by electron microscopy hardening that lead to its abrasion. This is the reason for the damage of the animals’ udder nipples during milking. A change in the image scale was performed by the radio- After working for 250 days/2,000 hours, microgaps technical equipment rather than the electronic-optical sys- and significant areas for the growth of bacterial colo- tem to form the image. nies (Fig. 3, c) are formed on nipple rubber. Rubber loses its The results of electron microscopy are shown in Fig. 4. gloss and gets dark.

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The studied parameters are important in determining the weight of the article changes by 8.5 %, the depth – by 37 %, usability of nipple rubber and broaden the idea of the mecha wall thickness – by 2.5 %, and stretching length – by 27 %. nism of its interaction with the environment.

5. 3. Studying the patterns of changes in the technical parameters of nipple rubber and establishing the nature of their influence It was established that during the process of milking, the nipple rubber is saturated with fat, loses elasticity, stretched, its surface gets coarse and is coated with cracks. This leads to the loss of its properties and negative phenomena mani- fested in the reduction of its massage action, an increase in the duration of milking, accumulation of milk fat and un- wanted microflora in rubber microcracks, the reduction of Fig. 6. Technical parameters of nipple rubber that change: the milk quality. The basic technological parameters that are А – inlet diameter; В – depth; С – stretching length; changed during the operation of nipple rubber are presented D – thickness in Table 6. The reasons for the change of the technical parameters of Table 6 nipple rubber are chemical and thermal loads. The effect of Changes taking place during the operation milk, water and detergents leads to saturation and swelling as of nipple rubber well as washing out of the material of nipple rubber. The higher the operating temperature, the operating pressure/vacuum, Specific features Changes over time the flow rate, the duration and frequency, the term of using Pulsation chamber is sealed from both ends of + the rubber, the more intensively these processes flow. a milking cup During the operation, the rubber changes its initial elas- Massage of cows’ udder nipple +++ ticity and shape. Consequently, during milking, the nipple Strength of connection with the udder nipple ++ rubber is raised and the udder nipple is pulled in. Fully-fledged and continuous milking of all When analyzing the results of the conducted research, +++ parts of cows’ udder both high positive and negative correlation dependencies between the technical parameters of nipple rubber were Simplicity of cleaning +++ found (Table 7). Permissibility of contact with food products – Note. «–» – no changes; «+» – insignificant change; «++» – Table 7 permissible change; «+++» – significant change Correlation dependence (r) of technological indicators of nipple rubber Thus, it was determined that the following parameters Indicator Correlation coefficient change substantially: massage of cows’ udder nipples, milk yield, and cleansing ability. The tightness of the coupling of Rubber stretching/service life –0.986 rubber with a milking cup does not change much during the Length of nipple rubber/service life +0.919 operation. Along with it, the strength of coupling with the Rubber stretching/rubber length –0.864 cow’ udder nipple changes substantially. The admissibility of the contact with food products during the entire period of use of a rubber article is in an unchanged state. Thus, it was determined that the length of the nipple Changes in the technical parameters of nipple rubber, rubber of milking cups is significantly affected by its service depending on the service life are shown in Fig. 5. life: r = +0.919. The inverse relation was found in the com- parison of rubber stretching to the service life and its length: R = –0.986 and r = –0.864. The tendency to reduction of stiffness of the nipple rubber depending on its operation period was establi shed (Table 8). It was found out that there is a close relationship between the stiffness of the nipple rubber and the intensity of milk yield. During the operation of the nipple rubber, it is stretched, which leads to a decrease in the stiffness of an article. Thus, if the stiffness in new nipple rubber was 3,120.46 ± 40.26 N/m, after 6 months of its use, the above indicator decreased up to 2,567.23 ± 37.65 N/m or by 1.2 times, which negatively affected the intensity of milk yield. Thus, when milking cows using new nipple rubber, the average milk yield intensity for a Fig. 5. Changes in the basic technical parameters group of cows was 1.98 ± 0.05 kg/min, and after 6 months this of nipple rubber indicator decreased by 1.1 times – up to 1.76 ± 0.03 kg/min. Along with this, a high positive correlation depen- It was found that all basic parameters of rubber are dence (r = +0.939) between the stiffness of nipple rubber and subject to changes during the operation (Fig. 6). Thus, the intensity of milk yield was established.

84 Engineering technological systems: Reference for Chief Mechanical Engineer at an industrial enterprise

Table 8 Dependence of intensity of milk yield on the stiffness of nipple rubber, (Х ± SX )

Service life Indicator new 1 month 2 months 3 months 4 months 5 months 6 months Stiffness of nipple 3,120.46 ± 40.26 2,970.28 ± 35.45 2,822.39 ± 38.32 2,707.25 ± 29.87 2,642.13 ± 32.94 2,597.41 ± 39.04 2,567.23 ± 37.65 rubber, N/m Milk yield 1.98 ± 0.05 1.97 ± 0.04 1.92 ± 0.04 1.89 ± 0.04 1.84 ± 0.05 1.81 ± 0.04 1.76 ± 0.03 intensity, kg/min Lim 1.41–2.16 1.40–2.00 1.42–2.00 1.36–1.93 1.32–1.84 1.30–1.73 1.27–1.63 Note: P < 0.01

6. Discussion of the results of studying the changes Subsequently, the regularities of changes in the technical in the technical parameters of nipple rubber for milking parameters of nipple rubber were revealed and the nature of machines that occur during operation their influence was established. Thus, the determined technological parameters that are changed during the operation of The analysis of numerous experiments [23–25] indicates nipple rubber were determined (Table 6). Advantages of the that the design of the rubber affects the characteristics of conducted research are the use of the points («–» – no changes; milking more than any other factor. Thus, at the initial stage «+» – insignificant change; «++» – admissible change; «+++» is of research, we set the purpose to establish the serviceability a substantial change) to determine the significance of the of nipple rubber of various manufacturers after operating factors in the overall technological process. In addition, for for 125 days/1,000 hours. It was proved that the geomet- clarity, the changes in the basic technical parameters of nipple rical parameters, such as the length of the operating part, rubber are presented in the form of a diagram (Fig. 5) and the diameter of the suction opening, the inner diameter of a scheme (Fig. 6). In the course of the research, we found the the tail part, undergo changes in the nipple rubber after the correlation dependences between the technical parameters of corresponding operating time. Stiffness and ovality of nipple nipple rubber (Table 7), which makes it possible to interpret rubbers change (Tables 2–5). The obtained results reveal the results in terms of the dependence of factors on each other. mechanism of a change in the operational characteristics of During the studies, it was found out that there is a close nipple rubber made of food silicone and rubber mixtures. This relationship between the stiffness of the nipple rubber and solves the problem of establishing the serviceability of these the intensity of milk yield (Table 8). The conducted stu elements of milking machines. dies (within 6 months) prove the fact that rubber stiffness In papers [26, 27], it was noted that the efficiency of changes every month, and these changes adversely affect cow milking is significantly influenced by the relevance of the milk yield intensity. This makes it possible to argue that the diameter of the inlet outing of the nipple rubber head, in order to ensure the physiological functioning of the ani- and the wall thickness of an article determines its physical mal’s breast, it is necessary to monitor constantly the state properties – the degree of softness/stiffness. The advantages of nipple rubber. of the conducted research over the specified ones include the The conducted studies are advantageously distinguished establishment of changes in the complex of technical indica- among the others [3, 7, 30] by their complexity, the use of tors, which fully reveals the picture of operational changes. innovative approaches (electron microscopy), and scalability. In paper [28], it is noted that it is necessary to monitor Along with this, due to the considerable variability of the constantly the degree of stiffness of nipple rubber. During structural values of nipple rubber, there occur some difficulties milking, too stiff rubber does not massage the entire area of in completely solving the problem if a rubber article meets the the udder nipple tip and presses the skin. When using such physiological needs of an animal. This remains a problematic rubber, the compression tact is reduced, which leads to the ir- part of the total technological process of milking. In addition, ritation of udder and cows falling ill with mastitis disease. The the experiments that are performed under industrial condi- conducted studies supplement the earlier obtained results. tions have a significant drawback, because they are carried out The inner surface of nipple rubber was studied at the next directly on animals. This causes special difficulties, because it stage with the use of electron microscopy. Fig. 3 shows the is difficult to choose the cows that are similar in their physio scheme of research. Using a raster electron microscope, the logy, and this significantly affects the results of the experiment, images were obtained (Fig. 4). The obtained results of elec- distorts actual information about the operation of the elements tron microscopy extend the understanding of the processes of a milking machine. In addition, one of the main disadvan- that flow during the operation of nipple rubber and make it tages of modern testing is that the procedure of complex tests possible to detect their influence on the inner surface of an of milking machines was not developed, there is no relation- article. Thus, the high resolution of an electron microscope ship between laboratory and production research. made it possible to observe objects and changes that lay At present, there is a huge selection of nipple rubber for beyond the resolution of other laboratory equipment. milking machines. The main thing is to take into conside In paper [29], it is emphasized that the application of rub- ration all its parameters and dimensions when buying, not to ber with even slight changes in shape can lead to a significant forget about the quality of the materials used in manufactur- deterioration in the state of the breast. Microscopic cracks on ing and to take proper care of it. The conducted studies offer the inner surface of rubber are the cause for different deposits, a real opportunity of taking into consideration the qualita- which are an ideal nutrient for bacteria. Conducted research tive parameters of nipple rubber during selecting it. proves this theory, make it possible to approach critically the With a large assortment of nipple rubber, there occurs issue of application of nipple rubber beyond the terms of its use. a need to carry out further research in the field of the selection

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of nipple rubber for a milking herd, chosen according to the pro- varies within significant limits and on average is: for arti- ductivity of animals. That is why the research aimed at estab- cles made of silicone 2,849.61 ± 52.23–3,343.76 ± 51.26 N/m; lishing the mechanism of the influence of nipple rubber, made articles made of the material of rubber mixtures – of different material, on cows’ udder nipple. This will make it 2,597.76 ± 78.26–2,821.43 ± 55.24 N/m. The readiness coeffi- possible to expand the area of both theoretical and practical cient of all articles is 1. knowledge in dairy cattle breeding, which would serve as 2. With the use of electron microscopy, it was found that a prerequisite to the improvement of milking equipment. there are changes in the internal surface of nipple rubber after operating for 125 days/1,000 hours and after the operation for 250 days/2,000 hours. 7. Conclusions 3. It was established that all the basic parameters of nipple rubber change during the operation: the weight of an 1. It was established that the serviceability of all nipple article changes by 8.5 %, the depth – by 37 %, the wall thick- rubbers was 1,000 hours, which after working for eight hours ness – by 2.5 %, and stretching length – by 27 %. The posi per day corresponds to 125 days or 4 months of operation. tive correlation between the stiffness of nipple rubber and After working for 1,000 hours, the stiffness of nipple rubber the intensity of cows’ milk yield (r = +0.939) was established.

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